U.S. Pat. No. 4,761,226, assigned to the assignee of the present invention, discloses a media filter filtration apparatus having an upper filter tank. The upper tank includes a perforate floor provided with a lower filtrate compartment covered with a filter media. The lower compartment is connected to the intake of a pump. The filter media, either a paper web or a fibrous filter aid, is supplied from a roll of the media and moved downwardly along an end wall of the tank and across the floor where the media is indexed by a conveyor. The filter media is moved and subsequently removed when contaminated by advancing the conveyor after any vacuum is relieved. A take-up mechanism is operated in connection with the indexing of the media to take-up the contaminated filter media.
In this arrangement, the filter media is unrolled each time the conveyor indexes. As the conveyor is started, the tension on the filter media causes the filter media to be unrolled. However, when the conveyor stops, the unrolling action of the media roll continues until frictional forces overcome the momentum of the unrolling action, whereby the media can become billowed before it is fed into the tank.